Originally known as “Decoration Day”, May 30th was established in 1868 by the leader of a Union Army veterans’ organization as a day to honor “comrades who died in defense of their country during the late rebellion.” After World War I, Americans began including those who had died in all of America's wars in the May 30th observances and in 1971, Congress declared Memorial Day a national holiday to be celebrated annually on the last Monday in May.